Caption: Waterspout formation. 19th-century artwork showing a waterspout forming over the sea. The whirlwind forms at left and extends to reach the sea at centre. This agitates the surface of the water, causing spray. At right the spray has become a vortex and is forming a continuous column with the cloud. Artwork from 'A Treatise on Meteorology: With a Collection of Meteorological Tables' (1868) by the American mathematician Elias Loomis (1811-1889).